This proposed program project focuses upon regulation of cell proliferation by steroid hormones. Three projects are proposed that deal with different aspects of the manner in which glucocorticoids, estrogens, and sterols regulate proliferation. Although the projects deal almost entirely with malignant cells, the phenomena to be investigated have direct relevance to regulatory processes that are common to growth control in both transformed and normal cells. The central hypothesis to be explored proposes that these compounds play a critical role in the neoplastic transformation and maintenance of the proliferative state. The individual projects address regulation of human lymphoid cells by oxysterols and glucocorticoids (Projects I and II) and mechanisms of estrogen induction of renal tumors in hamster kidneys (Project III).